Tracking original lead source with UTM info

I'm having trouble tracking lead sources in Marketo. I think the issue could be summed up like this: I'm looking for a way to track UTM info in Marketo. But I'll provide additional details below.

In particular, I'm wanting to ask some basic questions about my Marketo leads, such as: "Out of the 100 people that signed up for the on-demand webinar in March, which of them did so because they saw x advertisement?" For this example, I'm tracking conversion from a LinkedIn sponsored update.

We have what I assume to be a fairly normal setup:

Landing page. Simple page with a form for name, email, etc.

Video page. After filling out the form, they are redirected to the page with the on-demand video.

We have our Google Analytics code on our Marketo pages, and we of course add UTM info to our links, so I'm able to get the count without much trouble, via Google Analytics. I know how many people hit the landing page, and how many make it through to the video page, and exactly which ad they came from.

But once I get into Marketo to find out who these people are, I run into a problem. If I use the Original Referrer column, I see a mixture of things like these:

http://www.linkedin.com. This makes sense, but doesn't let me distinguish between paid and non-paid LinkedIn traffic. (The same thing happens with Twitter. We run some Twitter ads, but I want to distinguish between paid and non-paid Twitter traffic.)

Wow tall order. I think there are a couple of threads on this, but maybe not as complex.

Have you setup separate UTM fields to capture that info as they hit the form?

I'm pretty sure Original Referrer has this problem for everyone because it is a Marketo field and subject to vagaries of how referrer is passed. Otherwise, I can't be more help here. Has someone else worked on this scale?

Josh, thanks for the reply. Shortly after I posted this, I learned about creating custom UTM fields in Marketo and mapping the URL parameters to those fields. I think that's going to get me what I need. It doesn't sound trivial to set up correctly, but it should be manageable.

Just to add up to the scenario, how are you dealing with the fact that sometime a lead will land on your Website / landing page from an ad and then will leave. THen he will come back later either by a Search or direct visit and therefor you will have lost all the information about the original visit from the ad.

I have implemented a solution to help capture multiple touches a while back back and we are now implementing it again for other Marketo clients. Have a look at the slideshare document I presented at the Marketo User Summit in 2010 and let me know if that would help you acheiving your goals. I would be verry happy to get your feedback on this kind of solution.

@Bec, this is the solution I found in another thread (this links directly to the relevant comment): http://goo.gl/NkkTYV

@Alexandre, thanks for the link. I haven't checked it out yet since I've moved on to other projects at the moment, but it's great to have another option to try out. Regarding your first question, I think I was going to prevent the Marketo fields from getting overwritten. The solution at http://goo.gl/NkkTYV also had some notes about history, which might also help.